Liquid-cooling apparatus with integrated coolant filter

ABSTRACT

Cooling apparatuses, cooled electronic modules, and methods of fabrication are provided which facilitate heat transfer from an electronic component(s). The cooling apparatus includes a liquid-cooled heat sink with a thermally conductive structure having a coolant-carrying compartment including a region of reduced cross-sectional coolant flow area. The heat sink includes a coolant inlet and outlet in fluid communication with the compartment, and the region of reduced cross-sectional coolant flow area provides an increased effective heat transfer coefficient between a main heat transfer surface of the conductive structure and the coolant. The cooling apparatus further includes a coolant loop coupled to the coolant inlet and outlet to facilitate flow of coolant through the coolant-carrying compartment, and a coolant filter positioned to filter contaminants from the coolant passing through the heat sink. The coolant filter has a larger cross-sectional coolant flow area than the region of reduced cross-sectional coolant flow area.

BACKGROUND

As is known, operating electronic components produce heat. This heatshould be removed in an effective manner to maintain device junctiontemperatures within desirable limits, with failure to do so resulting inexcessive component temperatures, potentially leading to thermal runawayconditions. Several trends in the electronics industry have combined toincrease the importance of thermal management, including heat removalfor electronic components, including technologies where thermalmanagement has traditionally been less of a concern, such as CMOS. Inparticular, the need for faster and more densely packed circuits has hada direct impact on the importance of thermal management. First, powerdissipation, and therefore heat production, increases as deviceoperating frequencies increase. Second, increased operating frequenciesmay be possible at lower device junction temperatures. Further, as moreand more devices or components are packed onto a single chip, heat flux(Watts/cm²) increases, resulting in the need to dissipate more powerfrom a given size chip or module. These trends have combined to createapplications where it is no longer desirable to remove heat from moderndevices solely by traditional air cooling methods, such as by using aircooled heat sinks with heat pipes or vapor chambers. Such air coolingtechniques are inherently limited in their ability to extract heat froman electronic component with high power density.

The need to cool current and future high heat load, high heat fluxelectronic devices therefore mandates the development of aggressivethermal management techniques using, for instance, liquid cooling.

BRIEF SUMMARY

In one aspect, provided herein is a cooling apparatus, comprising aliquid-cooled heat sink, a coolant loop, and a coolant filter. Theliquid-cooled heat sink includes: a thermally conductive structure witha coolant-carrying compartment comprising, at least in part, a region ofreduced cross-sectional coolant flow area through which coolant flows; acoolant inlet and a coolant outlet associated with the thermallyconductive structure and in fluid communication with thecoolant-carrying compartment of the thermally conductive structure tofacilitate coolant flow therethrough; and wherein the region of reducedcross-sectional coolant area of the coolant-carrying compartmentprovides an increased effective heat transfer coefficient between a mainheat transfer surface of the thermally conductive structure and thecoolant within the coolant-carrying compartment of the liquid-cooledheat sink. The coolant loop is coupled to the coolant inlet and thecoolant outlet of the liquid-cooled heat sink to facilitate flow ofcoolant through the coolant-carrying compartment thereof, and thecoolant filter is positioned to filter contaminants from the coolantpassing through the liquid-cooled heat sink. The coolant filter has alarger cross-sectional flow area than the region of reducedcross-sectional flow area of the coolant-carrying compartment within thethermally conductive structure of the liquid-cooled heat sink.

In another aspect, a cooled electronic module is provided which includesat least one electronic component, and a cooling apparatus to facilitatecooling the at least one electronic component. The cooling apparatusincludes a liquid-cooled heat sink, a coolant loop, and a coolantfilter. The liquid-cooled heat sink includes: a thermally conductivestructure with a coolant-carrying compartment comprising, at least inpart, a region of reduced cross-sectional coolant flow area throughwhich coolant flows; a coolant inlet and a coolant outlet associatedwith the thermally conductive structure and in fluid communication withthe coolant-carrying compartment of the thermally conductive structureto facilitate coolant flow therethrough; and wherein the region ofreduced cross-sectional coolant flow area of the coolant-carryingcompartment provides an increased effective heat transfer coefficientbetween a main heat transfer surface of the thermally conductivestructure and the coolant within the coolant-carrying compartment of theliquid-cooled heat sink. The coolant loop is coupled to the coolantinlet and the coolant outlet of the liquid-cooled heat sink tofacilitate flow of coolant through the coolant-carrying compartmentthereof, and the coolant filter is positioned to filter contaminantsfrom the coolant passing through the liquid-cooled heat sink. Thecoolant filter has a larger cross-sectional flow area than the region ofreduced cross-sectional flow area of the coolant-carrying compartmentwithin the thermally conductive structure of the liquid-cooled heatsink.

In a further aspect, a method is provided which includes: providing aliquid-cooled heat sink configured to facilitate cooling at least oneelectronic component, the liquid-cooled heat sink comprising: athermally conductive structure with a coolant-carrying compartmentcomprising, at least in part, a region of reduced cross-sectionalcoolant flow area through which coolant flows; a coolant inlet and acoolant outlet associated with the thermally conductive structure and influid communication with the coolant-carrying compartment of thethermally conductive structure to facilitate coolant flow therethrough;wherein the region of reduced cross-sectional coolant flow area of thecoolant-carrying compartment provides an increased effective heattransfer coefficient between a main heat transfer surface of thethermally conductive structure and the coolant within thecoolant-carrying compartment; providing a coolant loop coupled to thecoolant inlet and the coolant outlet of the liquid-cooled heat sink tofacilitate flow of coolant through the coolant-carrying compartmentthereof; and providing a coolant filter positioned to filtercontaminants from the coolant passing through the liquid-cooled heatsink, the coolant filter having a larger cross-sectional coolant flowarea than the region of reduced cross-sectional coolant flow area of thecoolant-carrying compartment within the thermally conductive structureof the liquid-cooled heat sink.

Additional features and advantages are realized through the techniquesof the present invention. Other embodiments and aspects of the inventionare described in detail herein and are considered a part of the claimedinvention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One or more aspects of the present invention are particularly pointedout and distinctly claimed as examples in the claims at the conclusionof the specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1. depicts one embodiment of a conventional raised floor layout ofan air-cooled data center;

FIG. 2 depicts one embodiment of a coolant distribution unitfacilitating liquid-cooling of electronics racks of a data center, inaccordance with one or more aspects of the present invention;

FIG. 3 is a plan view of one embodiment of an electronic system (ornode) layout illustrating an air and liquid cooling apparatus forcooling components of the electronic system, in accordance with one ormore aspects of the present invention;

FIG. 4 depicts one detailed embodiment of a partially assembledelectronic system layout, wherein the electronic system includes eightheat-generating electronic components to be liquid-cooled, each having,in one embodiment, a respective cooling apparatus associated therewith,in accordance with one or more aspects of the present invention;

FIG. 5A depicts one embodiment of a cooled electronic module comprisingat least one electronic component and a cooling apparatus which includesa liquid-cooled heat sink, in accordance with one or more aspects of thepresent invention;

FIG. 5B depicts one embodiment of the liquid-cooled heat sink of FIG.5A, taken along line 5B-5B thereof, in accordance with one or moreaspects of the present invention;

FIG. 5C depicts a cross-sectional elevational view of the liquid-cooledheat sink of FIG. 5B, taken along line 5C-5C thereof, and shown with areplaceable coolant filter subassembly, in accordance with one or moreaspects of the present invention;

FIG. 5D depicts the liquid-cooled heat sink of FIG. 5C, with thereplaceable coolant filter subassembly removed from the liquid-cooledheat sink, in accordance with one or more aspects of the presentinvention;

FIG. 6A is a cross-sectional elevational view of an alternate embodimentof a liquid-cooled heat sink, in accordance with one or more aspects ofthe present invention;

FIG. 6B is a cross-sectional plan view of the liquid-cooled heat sink ofFIG. 6A, taken along line 6B-6B thereof, in accordance with one or moreaspects of the present invention;

FIG. 7A depicts an alternate embodiment of the partially assembledelectronic system layout of FIG. 4, wherein the cooling apparatusincludes a coolant filter subassembly, in accordance with one or moreaspects of the present invention;

FIG. 7B is a cross-sectional elevational view of one embodiment of thecoolant filter subassembly of FIG. 7A, in accordance with one or moreaspects of the present invention;

FIG. 7C depicts an alternate embodiment of a coolant filter subassembly(configured, in this example, as part of a coolant loop connectionsubassembly) for a liquid-cooling apparatus such as depicted in FIG. 7A,in accordance with one or more aspects of the present invention; and

FIG. 7D depicts the coolant filter subassembly of FIG. 7C uncoupled to,for instance, facilitate replacement of a filter or filtration mediacartridge, in accordance with one or more aspects of the presentinvention.

DETAILED DESCRIPTION

As used herein, the terms “electronics rack” and “rack unit” are usedinterchangeably, and unless otherwise specified include any housing,frame, rack, compartment, blade server system, etc., having one or moreheat-generating components of a computer system, electronic system, orinformation technology equipment, and may be, for example, a stand-alonecomputer processor having high, mid or low end processing capability. Inone embodiment, an electronics rack may comprise a portion of anelectronic system, a single electronic system, or multiple electronicsystems, for example, in one or more sub-housings, blades, books,drawers, nodes, compartments, etc., having one or more heat-generatingelectronic components disposed therein. An electronic system within anelectronics rack may be movable or fixed relative to the electronicsrack, with the rack-mounted electronic drawers and blades of a bladecenter system being two examples of systems of an electronics rack to becooled.

“Electronic component” refers to any heat-generating electroniccomponent of, for example, a computer system or other electronics unitrequiring cooling. By way of example, an electronic component maycomprise one or more integrated circuit die (or chips) and/or otherelectronic devices to be cooled, including one or more processor chips,memory chips and/or memory support chips. Further, the terms “heat sink”or “cold plate” refer to any thermally conductive structure having oneor more compartments, channels, passageways, etc., formed therein forthe flowing of coolant therethrough. In addition, “metallurgicallybonded” refers generally herein to two components being welded, brazedor soldered together by any means.

As used herein, a “liquid-to-liquid heat exchanger” may comprise, forexample, two or more coolant flow paths, formed of thermally conductivetubing (such as copper or other tubing) in thermal or mechanical contactwith each other. Size, configuration and construction of theliquid-to-liquid heat exchanger can vary without departing from thescope of the invention disclosed herein. Further, “data center” refersto a computer installation containing one or more electronics racks tobe cooled. As a specific example, a data center may include one or morerows of rack-mounted computing units, such as server units.

One example of the coolants discussed herein, such as the facilitycoolant or system coolant, is water. However, the cooling conceptsdisclosed herein are readily adapted to use with other types of coolanton the facility side and/or on the system side. For example, one or moreof the coolants may comprise a brine, a fluorocarbon liquid, ahydrofluoroether liquid, a liquid metal, or other similar coolant, orrefrigerant, while still maintaining the advantages and unique featuresof the present invention.

Reference is made below to the drawings, which are not drawn to scale tofacilitate an understanding thereof, wherein the same reference numbersused throughout different figures designate the same or similarcomponents.

FIG. 1 depicts one embodiment of a raised floor layout of an air cooleddata center 100 typical in the prior art, wherein multiple electronicsracks 110 are disposed in one or more rows. A data center such asdepicted in FIG. 1 may house several hundred, or even several thousandmicroprocessors. In the arrangement illustrated, chilled air enters thecomputer room via perforated floor tiles 160 from a supply air plenum145 defined between the raised floor 140 and a base or sub-floor 165 ofthe room. Cooled air is taken in through louvered covers at air inletsides 120 of the electronics racks and expelled through the back (i.e.,air outlet sides 130) of the electronics racks. Each electronics rack110 may have one or more air moving devices (e.g., fans or blowers) toprovide forced inlet-to-outlet airflow to cool the electronic deviceswithin the system(s) of the rack. The supply air plenum 145 providesconditioned and cooled air to the air-inlet sides of the electronicsracks via perforated floor tiles 160 disposed in a “cold” aisle of thecomputer installation. The conditioned and cooled air is supplied toplenum 145 by one or more air conditioning units 150, also disposedwithin the data center 100. Room air is taken into each air conditioningunit 150 near an upper portion thereof. This room air may comprise inpart exhausted air from the “hot” aisles of the computer installationdefined, for example, by opposing air outlet sides 130 of theelectronics racks 110.

Due to the ever-increasing airflow requirements through electronicsracks, and the limits of air distribution within the typical data centerinstallation, liquid-based cooling may, for instance, be combined withthe above-described conventional air-cooling. FIGS. 2-4 illustrate oneembodiment of a data center implementation employing a liquid-basedcooling system with one or more cold plates coupled to highheat-generating electronic components disposed within an electronicsrack.

In particular, FIG. 2 depicts one embodiment of a coolant distributionunit 200 for a data center. The coolant distribution unit isconventionally a relatively large unit which occupies what would beconsidered a full electronics frame. Within coolant distribution unit200 is a power/control element 212, a reservoir/expansion tank 213, aheat exchanger 214, a pump 215 (often accompanied by a redundant secondpump), facility water inlet 216 and outlet 217 supply pipes, a supplymanifold 218 supplying water or system coolant to the electronics racks210 via couplings 220 and lines 222, and a return manifold 219 receivingwater from the electronics racks 210, via lines 223 and couplings 221.Each electronics rack includes (in one example) a power/control unit 230for the electronics rack, multiple electronic systems 240, a systemcoolant supply manifold 250, and a system coolant return manifold 260.As shown, each electronics rack 210 is disposed on raised floor 140 ofthe data center with lines 222 providing system coolant to systemcoolant supply manifolds 250 and lines 223 facilitating return of systemcoolant from system coolant return manifolds 260 being disposed in thesupply air plenum beneath the raised floor.

In the embodiment illustrated, the system coolant supply manifold 250provides system coolant to the cooling systems of the electronic systems(more particularly, to liquid-cooled cold plates thereof) via flexiblehose connections 251, which are disposed between the supply manifold andthe respective electronic systems within the rack. Similarly, systemcoolant return manifold 260 is coupled to the electronic systems viaflexible hose connections 261. Quick connect couplings may be employedat the interface between flexible hoses 251, 261 and the individualelectronic systems. By way of example, these quick connect couplings maycomprise various types of commercially available couplings, such asthose available from Colder Products Company, of St. Paul, Minn., USA,or Parker Hannifin, of Cleveland, Ohio, USA.

Although not shown, electronics rack 210 may also include anair-to-liquid heat exchanger disposed at an air outlet side thereof,which also receives system coolant from the system coolant supplymanifold 250 and returns system coolant to the system coolant returnmanifold 260.

FIG. 3 depicts one embodiment of an electronic system 313 componentlayout wherein one or more air moving devices 311 provide forced airflow 315 to cool multiple components 312 within electronic system 313.Cool air is taken in through a front 331 and exhausted out a back 333 ofthe system. The multiple components to be cooled include multipleprocessor modules to which liquid-cooled cold plates 320 (of aliquid-based cooling system) are coupled, as well as multiple arrays ofmemory modules 330 (e.g., dual in-line memory modules (DIMMs)) andmultiple rows of memory support modules 332 (e.g., DIMM control modules)to which air-cooled heat sinks are coupled. In the embodimentillustrated, memory modules 330 and the memory support modules 332 arepartially arrayed near front 331 of electronic system 313, and partiallyarrayed near back 333 of electronic system 313. Also, in the embodimentof FIG. 3, memory modules 330 and the memory support modules 332 arecooled by air flow 315 across the electronic system.

The illustrated liquid-based cooling system further includes multiplecoolant-carrying tubes connected to and in fluid communication withliquid-cooled cold plates 320. The coolant-carrying tubes comprise setsof coolant-carrying tubes, with each set including (for example) acoolant supply tube 340, a bridge tube 341 and a coolant return tube342. In this example, each set of tubes provides liquid coolant to aseries-connected pair of cold plates 320 (coupled to a pair of processormodules). Coolant flows into a first cold plate of each pair via thecoolant supply tube 340 and from the first cold plate to a second coldplate of the pair via bridge tube or line 341, which may or may not bethermally conductive. From the second cold plate of the pair, coolant isreturned through the respective coolant return tube 342. Note that in analternate implementation, each liquid-cooled cold plate 320 could becoupled directly to a respective coolant supply tube 340 and coolantreturn tube 342, that is, without series connecting two or more of theliquid-cooled cold plates.

FIG. 4 depicts in greater detail an alternate electronic system layoutcomprising eight processor modules, each having a respectiveliquid-cooled cold plate of a liquid-based cooling system coupledthereto. The liquid-based cooling system is shown to further includeassociated coolant-carrying tubes for facilitating passage of liquidcoolant through the liquid-cooled cold plates and a header subassemblyto facilitate distribution of liquid coolant to and return of liquidcoolant from the liquid-cooled cold plates. By way of specific example,the liquid coolant passing through the liquid-based cooling subsystem iscooled and conditioned (e.g., filtered) water.

FIG. 4 is an isometric view of one embodiment of an electronic system ordrawer, and monolithic cooling system. The depicted planar serverassembly includes a multi-layer printed circuit board to which memoryDIMM sockets and various electronic components to be cooled are attachedboth physically and electrically. In the cooling system depicted, asupply header is provided to distribute liquid coolant from a singleinlet to multiple parallel coolant flow paths and a return headercollects exhausted coolant from the multiple parallel coolant flow pathsinto a single outlet. Each parallel coolant flow path includes one ormore cold plates in series flow arrangement to facilitate cooling one ormore electronic components to which the cold plates are mechanically andthermally coupled. The number of parallel paths and the number ofseries-connected liquid-cooled cold plates depends, for example, on thedesired component temperature, available coolant temperature and coolantflow rate, and the total heat load being dissipated from each electroniccomponent.

More particularly, FIG. 4 depicts a partially assembled electronicsystem 413 and an assembled liquid-based cooling system 415 coupled toprimary heat-generating components (e.g., including processor die) to becooled. In this embodiment, the electronic system is configured for (oras) a node of an electronics rack, and includes, by way of example, asupport substrate or planar board 405, a plurality of memory modulesockets 410 (with the memory modules (e.g., dual in-line memory modules)not shown), multiple rows of memory support modules 432 (each havingcoupled thereto an air-cooled heat sink 434), and multiple processormodules (not shown) disposed below the liquid-cooled cold plates 420 ofthe liquid-based cooling system 415.

In addition to liquid-cooled cold plates 420, liquid-based coolingsystem 415 includes multiple coolant-carrying tubes, including coolantsupply tubes 440 and coolant return tubes 442 in fluid communicationwith respective liquid-cooled cold plates 420. The coolant-carryingtubes 440, 442 are also connected to a header (or manifold) subassembly450 which facilitates distribution of liquid coolant to the coolantsupply tubes and return of liquid coolant from the coolant return tubes442. In this embodiment, the air-cooled heat sinks 434 coupled to memorysupport modules 432 closer to front 431 of electronic system 413 areshorter in height than the air-cooled heat sinks 434′ coupled to memorysupport modules 432 near back 433 of electronic system 413. This sizedifference is to accommodate the coolant-carrying tubes 440, 442 since,in this embodiment, the header subassembly 450 is at the front 431 ofthe electronics drawer and the multiple liquid-cooled cold plates 420are in the middle of the drawer.

By way of example, liquid-based cooling system 415 comprises (in oneembodiment) a pre-configured monolithic structure which includesmultiple (pre-assembled) liquid-cooled cold plates 420 configured anddisposed in spaced relation to engage respective heat-generatingelectronic components. Each liquid-cooled cold plate 420 includes, inthis embodiment, a liquid coolant inlet and a liquid coolant outlet, aswell as an attachment subassembly (i.e., a cold plate/load armassembly). Each attachment subassembly is employed to couple itsrespective liquid-cooled cold plate 420 to the associated electroniccomponent to form the cold plate and electronic component (or device)assemblies. Alignment openings (i.e., thru-holes) are provided on thesides of the cold plate to receive alignment pins or positioning dowelsduring the assembly process. Additionally, connectors (or guide pins)are included within attachment subassembly, which facilitate use of theattachment assembly.

As shown in FIG. 4, header subassembly 450 includes two liquidmanifolds, i.e., a coolant supply header 452 and a coolant return header454, which in one embodiment, are coupled together via supportingbrackets. In the monolithic cooling structure of FIG. 4, the coolantsupply header 452 is metallurgically bonded in fluid communication toeach coolant supply tube 440, while the coolant return header 454 ismetallurgically bonded in fluid communication to each coolant returntube 452. A single coolant inlet 451 and a single coolant outlet 453extend from the header subassembly for coupling to the electronicsrack's coolant supply and return manifolds (not shown).

FIG. 4 also depicts one embodiment of the pre-configured,coolant-carrying tubes. In addition to coolant supply tubes 440 andcoolant return tubes 442, bridge tubes or lines 441 are provided forcoupling, for example, a liquid coolant outlet of one liquid-cooled coldplate to the liquid coolant inlet of another liquid-cooled cold plate toconnect in series fluid flow the cold plates, with the pair of coldplates receiving and returning liquid coolant via a respective set ofcoolant supply and return tubes. In one embodiment, the coolant supplytubes 440, bridge tubes 441 and coolant return tubes 442 are eachpre-configured, semi-rigid tubes formed of a thermally conductivematerial, such as copper or aluminum, and the tubes are respectivelybrazed, soldered or welded in a fluid-tight manner to the headersubassembly and/or the liquid-cooled cold plates. The tubes arepre-configured for a particular electronics system to facilitateinstallation of the monolithic structure in engaging relation with theelectronic system.

As noted, the need to cool current and future high-heat load andhigh-heat flux electronic components requires the development ofextremely aggressive thermal management techniques, such asliquid-cooling using jet impingement techniques and/or fin-based orpin-based cold plate devices. Possible issues with liquid coolinginclude, for instance, sealing, clogging due to particle contamination,thermal conductivity of the cold plate material, effectiveness of thethermal interface to the electronics, thermal expansion mismatch betweenthe cold plate and the electronic components to be cooled, andmanufacturability.

Often, the liquid-cooled heat sink or cold plate can operate in thefully-developed laminar regime, in which the Nusselt number issubstantially constant with respect to fluid velocity in the fullydeveloped region through the fin gaps. Under such conditions, in orderto improve the thermal performance of the heat sink, there is a desireto use a finned or pinned array structure that has very small hydrauliccross-sectional flow areas, so as to increase the heat transfercoefficient (that is, at a constant Nusselt number). To date,liquid-cooled cold plates with fin channel gaps, for instance, 1.5 mm orgreater have been used. However, there is interest in further reducingthe channel spacing, that is, the hydraulic cross-sectional flow areato, for instance, 0.3 mm or below, which will introduce greater risk ofchannel clogging due to particulate contamination, with the relatedissues of lower thermal performance due to ineffective channels, and alower liquid flow rate due to a higher cold plate pressure drop.

In view of this, disclosed herein are various cooling apparatusescomprising various liquid-cooled heat sinks or cold plates, which haveintegral coolant filters or integral coolant filter subassembliesassociated with the liquid-cooled heat sink, or a coolant loop whichfeeds coolant through the liquid-cooled heat sink.

In one aspect, disclosed below is a cooling apparatus which includes aliquid-cooled heat sink having a thermally conductive structure with acoolant-carrying compartment comprising, at least in part, a region ofreduced cross-sectional coolant flow area through which coolant flows.For instance, the coolant-carrying compartment may have one or moreregions with coolant flow openings or channels less than 0.5 mm incritical dimension. In certain embodiments, the coolant flows in adirection, at least partially, substantially parallel to a main heattransfer surface of the thermally conductive structure, for example,parallel to a main heat transfer surface to which one or more electroniccomponents to be cooled are coupled, and across which heat istransferred from the electronic component(s) to the heat sink. Theliquid-cooled heat sink further includes a coolant inlet and a coolantoutlet associated with the thermally conductive structure and in fluidcommunication with the coolant-carrying compartment of the thermallyconductive structure to facilitate coolant flow therethrough. The regionof reduced cross-sectional coolant flow area of the coolant-carryingcompartment is configured to provide an increased effective heattransfer coefficient between a main heat transfer surface of thethermally conductive structure and the coolant within thecoolant-carrying compartment. The cooling apparatus further includes acoolant loop coupled to the coolant inlet and the coolant outlet of theliquid-cooled heat sink to facilitate flow of coolant through thecoolant-carrying compartment, and a coolant filter positioned to filtercontaminants from the coolant passing through the liquid-cooled heatsink, the coolant filter having a larger cross-sectional coolant flowarea than a coolant flow area of the region of reduced cross-sectionalcoolant flow area of the coolant-carrying compartment within thethermally conductive structure of the liquid-cooled heat sink.

For example, in one embodiment, the thermally conductive structure maybe configured with an increasing wetted surface area within thecoolant-carrying compartment in the direction of coolant flow; that is,may be configured with an increasing surface area exposed to the coolantflow on which the increasing effective heat transfer coefficient mayact. In another embodiment, the thermally conductive structure mayinclude multiple coolant flow regions serially coupled in fluidcommunication within the coolant flow compartment, wherein thecross-sectional coolant flow area may vary between coolant flow regionsof the multiple coolant flow regions of the coolant-carrying compartmentof the thermally conductive structure. By way of example, the multiplecoolant flow regions may include multiple thermally conductive finregions, wherein one or more fin region characteristics or attributesmay vary between different thermally conductive fin regions of themultiple thermally conductive fin regions. For instance, in oneembodiment, a size of thermally conductive fins may increase from onethermally conductive fin region to another thermally conductive finregion of the multiple thermally conductive fin regions, whichfacilitates providing a reduced cross-sectional coolant flow area in theanother thermally conductive fin region compared with the one thermallyconductive fin region, wherein the one thermally conductive fin regionis upstream of the another thermally conductive fin region in thedirection of coolant flow through the coolant-carrying compartment.

In another example, a number of thermally conductive fins may increasefrom one thermally conductive fin region to another thermally conductivefin region of the multiple thermally conductive fin regions, whichfacilitates providing a reduced cross-sectional coolant flow area in theanother thermally conductive fin region compared to the one thermallyconductive fin region, wherein the one thermally conductive fin regionis upstream of the another thermally conductive fin region in thedirection of coolant flow through the coolant-carrying compartment.

As a specific example, a size of thermally conductive fins may increasefrom a first thermally conductive fin region to a second thermallyconductive fin region of the multiple thermally conductive fin regions,which facilitates reducing the cross-sectional coolant flow area in thesecond thermally conductive fin region compared with the first thermallyconductive fin region, and a number of thermally conductive fin regionsmay increase from the second thermally conductive fin region to a thirdthermally conductive fin region of the multiple thermally conductive finregions, which further reduces the cross-sectional coolant flow area inthe third thermally conductive fin region compared with the secondthermally conductive fin region. In this example, the first thermallyconductive fin region is upstream of the second thermally conductive finregion, and the second thermally conductive fin region is upstream ofthe third thermally conductive fin region in the direction of coolantflow through the coolant-carrying compartment of the thermallyconductive structure.

In one implementation, the coolant-cooled heat sink includes a coolantinlet manifold region and a coolant outlet manifold region within thecoolant-carrying compartment, the coolant inlet manifold regionreceiving coolant from the coolant inlet, and the coolant outletmanifold region exhausting coolant from the coolant outlet, wherein theone or more reduced coolant flow regions are disposed between thecoolant inlet manifold region and the coolant outlet manifold region. Inanother embodiment, the region of reduced coolant flow may comprisemultiple thermally conductive pin fin regions, and wherein one thermallyconductive pin fin region of the multiple thermally conductive pin finregions may comprise pin fins of different sizes, with smaller pin finsbeing interspersed among larger pin fins. Further, in an implementationwhere the thermally conductive fins comprise pin fins, density of thethermally conductive pin fins may increase from one thermally conductivefin region to another thermally conductive fin region, which facilitatesproviding a reduced transverse coolant flow area in the anotherthermally conductive fin region compared to the one thermally conductivefin region, wherein the one thermally conductive fin region is upstreamof the another thermally conductive fin region in the direction ofcoolant flow through the coolant-carrying compartment.

Various embodiments of the coolant filter (or coolant filtersubassembly) are provided below. For instance, in one or moreembodiments, the coolant filter is positioned within the thermallyconductive structure of the liquid-cooled heat sink upstream of theregion of reduced cross-sectional coolant flow area within thecoolant-carrying compartment. In one embodiment, the cross-sectionalcoolant flow area of the coolant filter is at least twice as large asthe cross-sectional coolant flow area of the region of reducedcross-sectional coolant flow area of the coolant-carrying compartmentwithin the thermally conductive structure of the liquid-cooled heatsink, and the region of reduced cross-sectional coolant flow areaincludes one or more coolant flow openings or channels with a criticalcoolant flow dimension less than 0.5 mm.

In another implementation, the coolant filter is replaceable,notwithstanding that the liquid-cooled heat sink remains coupled to theat least one electronic component to be cooled. In anotherimplementation, the coolant-carrying compartment may comprise aconverging inlet plenum converging towards the region of reducedcross-sectional coolant flow area, and the coolant filter may bedisposed within the converging inlet plenum. In another embodiment, thecoolant filter encircles the region of reduced cross-sectional coolantflow area within the thermally conductive structure of the liquid-cooledheat sink. In this embodiment, coolant traverses through at least aportion of the reduced cross-sectional coolant flow area of thecoolant-carrying compartment of the thermally conductive structure, andexhausts from the thermally conductive structure over the region ofreduced cross-sectional coolant flow area.

In certain embodiments, the coolant filter is associated with thecoolant loop to filter the coolant before ingressing via the coolantinlet into the coolant-carrying compartment of the thermally conductivestructure of the liquid-cooled heat sink. For instance, the coolantfilter may be disposed within a coolant filter subassembly whichincludes a first end and a second end, which couple in fluidcommunication with the coolant loop to facilitate flow of coolant withinthe coolant loop through the coolant filter. The first end and thesecond end of the coolant filter subassembly may comprise a first quickconnect coupler and a second quick connect coupler, respectively. Inanother implementation, the coolant filter is disposed upstream of theliquid-cooled heat sink within a coolant loop connection subassembly,wherein the cross-sectional coolant flow area of the coolant filter islarger than a transverse cross-sectional coolant flow area of thecoolant loop.

As a specific example, FIGS. 5A-5D depict one embodiment of a cooledelectronic module, generally denoted 500, in accordance with one or moreaspects of the present invention. Referring collectively to FIGS. 5A-5D,cooled electronic module 500 includes one or more electronic components501 to be cooled and a liquid-cooled heat sink 510 coupled to theelectronic component(s) 501 to facilitate transfer of heat from thecomponent to, for instance, a liquid coolant passing throughliquid-cooled heat sink 510. In one example, the liquid coolant maycomprise a system coolant distributed such as described above inconnection with FIGS. 2-4.

Liquid-cooled heat sink 510 includes a thermally conductive structure502, such as a thermally conductive casing or housing, fabricated (forinstance) of a metal, which includes a coolant-carrying compartment(e.g., chamber, channel, tube, passageway, etc.), through which coolantflows in a direction 505 through the compartment from a coolant inlet511 to a coolant outlet 512 of the liquid-cooled heat sink 510. In thisexample, thermally conductive structure 502 includes a main heattransfer surface 504 coupled to and in thermal communication with theelectronic component(s) 501 to facilitate heat transfer from thecomponent(s) to the heat sink, and hence, to the coolant flowing throughthe heat sink. As one example, this main heat transfer surface maycomprise the base surface of the liquid-cooled heat sink, configured asdisclosed herein.

As illustrated in the cross-sectional plan view of FIG. 5B, andcross-sectional elevational views of FIGS. 5C & 5D, liquid-cooled heatsink 510 includes within the coolant-carrying compartment, a coolantinlet manifold 513 and a coolant outlet manifold 514, disposed adjacentto coolant inlet 511 and coolant outlet 512, respectively. Coolant inletmanifold 513 is, by way of example, a converging inlet manifold, whichfacilitates ensuring a lower velocity of liquid flow across a coolantfilter 522 disposed within the coolant inlet manifold 513, and thusresults in a lower pressure drop. The coolant outlet manifold 514 may bediverging (as illustrated) to further facilitate coolant flow throughthe coolant-carrying compartment of the liquid-cooled heat sink.

Coolant inlet manifold 513 receives coolant from the coolant inlet 511,and coolant outlet manifold 514 exhausts coolant from thecoolant-carrying compartment through the coolant outlet 512. Disposedbetween the coolant inlet and the coolant outlet manifolds 513, 514 areone or more coolant flow regions 515. The coolant flow region(s) 515 is,by way of example, at least one region of reduced cross-sectionalcoolant flow area through which coolant flows. For instance, a pluralityof plate fins 516 may be arrayed in parallel with small coolant flowchannels 517 formed between the plate fins 516.

Each coolant flow channel may comprise a transverse cross-sectionalcoolant flow area (or opening) with a critical coolant flow dimensionof, for instance, less than 0.5 mm. For example, the critical dimensionmay be 0.3 mm or less. Note that various regions of reducedcross-sectional coolant flow area may be provided within thecoolant-carrying compartment of liquid-cooled heat sink 510. Forinstance, multiple regions of reduced coolant flow area may be providedwith differing cross-sectional coolant flow areas, as noted above.Further, note that parallel plate fins 516 are presented by way ofexample only. In one or more other embodiments, pin fins could beclosely spaced such that one or more regions of reduced cross-sectionalcoolant flow area are defined as part of the coolant-carryingcompartment using the pin fins.

With one or more coolant flow openings (or transverse cross-sectionalareas) through one or more channels of the reduced cross-sectionalcoolant flow area having a critical coolant flow dimension less than 0.5mm, particulate filtering from the coolant is desirable. In theembodiments of FIGS. 5A-5D, the coolant filter 522 is part of a coolantfilter subassembly 520, and is replaceable while the liquid-cooled heatsink 510 remains physically coupled to the one or more electroniccomponents 501 to be cooled.

As illustrated in FIGS. 5C & 5D, coolant filter subassembly 520 may beattached, for example, using threaded fasteners, to an upper surface ofthe thermally conductive structure 502, with the coolant filter 522extending into the coolant inlet plenum 513. A fluid-tight seal may beaccomplished using an O-ring 523, sized to reside in an appropriatelyformed channel 524 in the upper surface of liquid-cooled heat sink 510.One or more fasteners 525 may be employed to secure coolant filtersubassembly 520 to the liquid-cooled heat sink 510, as well as tofacilitate removal of coolant filter subassembly 520 from theliquid-cooled heat sink 510, for instance, to replace coolant filter522. FIG. 5C illustrates coolant filter subassembly 520 in operationalstate, and FIG. 5D illustrates the coolant filter subassembly removed,for instance, to inspect or replace coolant filter 522.

In the above-described embodiment, liquid-cooled heat sink 510 of cooledelectronic module 500 advantageously includes an integrated (orembedded) particulate filtration media inside the heat sink or coldplate. The particulate filtration media, also referred to herein as thecoolant filter, comprises a filter or screen through or across whichliquid coolant flows to remove particulate contamination from the liquidcoolant. The coolant filter is sized and positioned so that the filterwill capture the particulates, with no impact on the heat transfersurface area within the region of reduced cross-sectional coolant flow515. Additionally, note that coolant filter 522 has a significantlylarger transverse cross-sectional coolant flow area than the totaltransverse coolant flow areas (or openings) within the region of reducedcross-sectional coolant flow area. The larger filtration surface areaexposed to the incoming liquid coolant will result in a longer life forthe filter, with a lower pressure drop across the filter, even in theevent of moderate particulate contamination within the liquid coolant.

The coolant filter or filtration media advantageously captures particlesand prevents degradation of thermal performance in the region of reducedcross-sectional coolant flow area of the heat sink by preventingparticulates from reaching and clogging the smaller coolant flowopenings within the region of reduced cross-sectional coolant flow area.As one example, one or more critical dimensions of the coolant flowopenings may be less than 0.5 mm within this region of reducedcross-sectional coolant flow area. Provision of a converging coolantinlet plenum advantageously allows for a lower surface velocity throughthe embedded coolant filter, and thus lowers the pressure drop acrossthe filter.

The coolant filter may be fabricated of any desired filter or screenmaterial, for instance, a porous material, such as a plastic, syntheticfiber, natural fiber, metal foam, etc., with pore sizes less than thecritical dimension for coolant flow through the region(s) of reducedcross-sectional coolant flow area. In one specific example, the coolantfilter may be a porous copper filter or screen brazed inside a copperheat sink, or in the example of FIGS. 5A-5D, brazed to the lid 521 ofthe coolant filter subassembly 520 for replacement with the subassembly.In the various embodiments disclosed herein, the coolant filter (orfiltration media) has openings which are smaller than the coolant flowopenings within the region of reduced cross-sectional coolant flow areaof the coolant-carrying compartment within the liquid-cooled heat sinkin order to trap any particulates within the filter.

FIGS. 6A-6B depict another embodiment of a cooling apparatus, generallydenoted 600, comprising a liquid-cooled heat sink 610, in accordancewith one or more aspects of the present invention. Referringcollectively to FIGS. 6A & 6B, liquid-cooled heat sink 610 includes athermally conductive structure 602, such as a thermally conductivecasing or housing, which defines a coolant-carrying compartment (orchamber, passageway, etc.), through which coolant flows from a coolantinlet 611 to a coolant outlet 612. The coolant-carrying compartmentincludes one or more regions 615 of reduced cross-sectional coolant flowarea, which may be configured such as described above in connection withthe embodiment of FIGS. 5A-5D. In the current embodiment, coolant filter622 is an embedded filtration media that encircles the region(s) 615 ofreduced cross-sectional coolant flow area. For instance, coolant filter622 may be disposed within a coolant inlet manifold 613 in fluidcommunication with coolant inlet 611, with the coolant outlet 612 beingdisposed over the region(s) 615 of reduced coolant flow area such thatcoolant flow 625 is initially through coolant filter 622, and then intoand up from, region(s) 615 of reduced coolant flow area to coolantoutlet 612, as illustrated in FIG. 6A. More particularly, after passingthrough the coolant filter, coolant flow 625 enters the region(s) 615 ofreduced coolant flow area (e.g., a fin array such as described above)and travels inwards for a distance, towards the center of region 615. Atthe middle, the coolant enters, for instance, a coolant outlet plenum(not shown) that runs along the width of the fin array, which is influid communication with coolant outlet 612 to exhaust coolant from theliquid-cooled heat sink 610.

Advantageously, the configuration of FIGS. 6A & 6B provides an evenlarger surface area for coolant filter 622, and thus a longer life forthe coolant filter. This design also provides a lower pressure dropthrough the coolant filter because of the enlarged size of the filter,compared with, for instance, the embodiments of FIGS. 5A-5D.

FIG. 7A depicts an alternate embodiment of the partially-assembledelectronic system layout of FIG. 4, wherein the coolant apparatusincludes a coolant filter subassembly 700 positioned at the coolantinlet to coolant supply header 452 of header assembly 450. Note thatthis positioning is provided by way of example only, and in otherembodiments, coolant filter subassembly 700 could be located closer tothe respective liquid-cooled cold plates or heat sinks 420 of thecoolant apparatus.

FIG. 7B is a cross-sectional elevational view of one embodiment ofcoolant filter subassembly 700. As illustrated, coolant filtersubassembly 700 includes a casing (or housing) 701 which has a largercross-sectional coolant flow area in a central region thereof, withinwhich a coolant filter 710 is disposed. The coolant filter subassembly700 further includes a first end 702 and a second end 703, each of whichmay include a fluidic interconnectors 704, 705, respectively. In oneembodiment, fluidic interconnector 704, 705 may be respective quickconnect couplings to facilitate, for instance, coupling of the coolantfilter subassembly to the header subassembly 450 in the example of FIG.7A. In operation, coolant flowing through the coolant loop (not shown)flows through first end 702 to a coolant supply manifold 711, and fromcoolant supply plenum 711, through coolant filter 710, to a coolantexhaust manifold 712, from which coolant is exhausted via second end703.

FIGS. 7C & 7D depict an alternate embodiment of a coolant filtersubassembly, in accordance with one or more aspects of the presentinvention. In this embodiment, the coolant filter subassembly isconfigured as a coolant loop connection subassembly 700′, which includesa first coolant loop conduit 720 and a second coolant loop conduit 721,configured with an enlarged, fluidic interconnect region sized toaccommodate a coolant filter 730, as well as to provide a coolant inletmanifold 731 and a coolant outlet manifold 732 to facilitate flow ofcoolant through coolant inlet 730. As illustrated, the coolant flow area(or surface area) of coolant filter 730 is larger, in one embodiment,than the transverse cross-sectional coolant flow area of coolant througheither the first coolant loop conduit 720 or second coolant loop conduit721. An O-ring 723 and appropriate fasteners 722 may be provided toensure a fluid-tight coupling between the first and second coolant loopconduits 720, 721.

Note that the configurations of FIGS. 7A & 7B and FIGS. 7C & 7Dadvantageously provide filtration to a liquid-cooled assembly outside ofthe liquid-cooled heat sinks, and thus, in these embodiments, onecoolant filter may filter particulate from coolant for multiple heatsinks. Also, note that, in the embodiments of FIGS. 7A-7D, the coolantfilter may be readily replaced by temporarily suspending coolant flowthrough the cooling assembly, and opening the appropriate interconnectsto replace the coolant filter. In the embodiment of FIGS. 7A & 7B, theentire coolant filter subassembly may be field-replaceable, while in theembodiment of FIGS. 7C & 7D, only the coolant filter itself need bereplaced.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” (andany form of comprise, such as “comprises” and “comprising”), “have” (andany form of have, such as “has” and “having”), “include” (and any formof include, such as “includes” and “including”), and “contain” (and anyform contain, such as “contains” and “containing”) are open-endedlinking verbs. As a result, a method or device that “comprises”, “has”,“includes” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises”, “has”, “includes” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of the present invention has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the invention in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.

What is claimed is:
 1. A cooling apparatus comprising: a liquid-cooledheat sink configured to cool at least one electronic component, theliquid-cooled heat sink comprising: a thermally conductive structurewith a coolant-carrying compartment comprising, at least in part, aregion of reduced cross-sectional coolant flow area through whichcoolant flows; a coolant inlet and a coolant outlet associated with thethermally conductive structure and in fluid communication with thecoolant-carrying compartment of the thermally conductive structure tofacilitate coolant flow therethrough; wherein the region of reducedcross-sectional coolant flow area of the coolant-carrying compartmentprovides an increased effective heat transfer coefficient between a mainheat transfer surface of the thermally conductive structure and thecoolant within the coolant-carrying compartment; a coolant loop coupledto the coolant inlet and the coolant outlet of the liquid-cooled heatsink to facilitate flow of coolant through the coolant-carryingcompartment thereof; and a coolant filter positioned to filtercontaminants from the coolant passing through the liquid-cooled heatsink, the coolant filter having a larger cross-sectional coolant flowarea than the region of reduced cross-sectional coolant flow area of thecoolant-carrying compartment within the thermally conductive structureof the liquid-cooled heat sink.
 2. The cooling apparatus of claim 1,wherein the coolant filter is positioned within the thermally conductivestructure of the liquid-cooled heat sink upstream of the region ofreduced cross-sectional coolant flow area of the coolant-carryingcompartment.
 3. The cooling apparatus of claim 2, wherein thecross-sectional coolant flow area of the coolant filter is at leasttwice as large as the cross-sectional coolant flow area of the region ofreduced cross-sectional coolant flow area of the coolant-carryingcompartment within the thermally conductive structure of theliquid-cooled heat sink.
 4. The cooling apparatus of claim 2, whereinthe coolant filter is replaceable, with the liquid-cooled heat sinkcoupled to the at least one electronic component to be cooled.
 5. Thecooling apparatus of claim 2, wherein the coolant-carrying compartmentcomprises a converging inlet plenum converging towards the region ofreduced cross-sectional coolant flow area, and wherein the coolantfilter is disposed within the converging inlet plenum.
 6. The coolingapparatus of claim 2, wherein the coolant filter encircles the region ofreduced cross-sectional coolant flow area.
 7. The cooling apparatus ofclaim 6, wherein the coolant traverses through at least a portion of thereduced cross-sectional coolant flow area of the coolant-carryingcompartment of the thermally conductive structure and exhausts from thethermally conductive structure over the region of reducedcross-sectional coolant flow area.
 8. The cooling apparatus of claim 1,wherein the coolant filter is associated with the coolant loop forfiltering the coolant before ingressing via the coolant inlet into thecoolant-carrying compartment of the thermally conductive structure ofthe liquid-cooled heat sink.
 9. The cooling apparatus of claim 8,wherein the coolant filter is disposed within a coolant filtersubassembly, the coolant filter subassembly comprising a first end and asecond end which couple in fluid communication with the coolant loop tofacilitate flow of coolant within the coolant loop through the coolantfilter, the first end and the second end comprising a first quickconnect coupler and a second quick connect coupler, respectively. 10.The cooling apparatus of claim 8, wherein the coolant filter is disposedupstream of the liquid-cooled heat sink within a coolant loop connectionsubassembly, wherein the cross-sectional coolant flow area of thecoolant filter is larger than a cross-sectional coolant flow area of thecoolant loop.
 11. The cooling apparatus of claim 1, wherein the regionof reduced cross-sectional coolant flow area comprises a coolant flowopening with a critical coolant flow dimension less than 0.5 mm.
 12. Acooled electronic module comprising: at least one electronic componentto be cooled; and a cooling apparatus to facilitate cooling of the atleast one electronic component, the cooling apparatus comprising: aliquid-cooled heat sink coupled to the at least one electronic componentto be cooled, the liquid-cooled heat sink comprising: a thermallyconductive structure with a coolant-carrying compartment comprising, atleast in part, a region of reduced cross-sectional coolant flow areathrough which coolant flows; a coolant inlet and a coolant outletassociated with the thermally conductive structure and in fluidcommunication with the coolant-carrying compartment of the thermallyconductive structure to facilitate coolant flow therethrough; whereinthe region of reduced cross-sectional coolant flow area of thecoolant-carrying compartment provides an increased effective heattransfer coefficient between a main heat transfer surface of thethermally conductive structure and the coolant within thecoolant-carrying compartment; a coolant loop coupled to the coolantinlet and the coolant outlet of the liquid-cooled heat sink tofacilitate flow of coolant through the coolant-carrying compartmentthereof; and a coolant filter positioned to filter contaminants from thecoolant passing through the liquid-cooled heat sink, the coolant filterhaving a larger cross-sectional coolant flow area than the region ofreduced cross-sectional coolant flow area of the coolant-carryingcompartment within the thermally conductive structure of theliquid-cooled heat sink.
 13. The cooled electronic module of claim 12,wherein the coolant filter is positioned within the thermally conductivestructure of the liquid-cooled heat sink upstream of the region ofreduced cross-sectional coolant flow area of the coolant-carryingcompartment.
 14. The cooled electronic module of claim 13, wherein thecross-sectional coolant flow area of the coolant filter is at leasttwice as large as the cross-sectional coolant flow area of the region ofreduced cross-sectional coolant flow area of the coolant-carryingcompartment within the thermally conductive structure of theliquid-cooled heat sink.
 15. The cooled electronic module of claim 13,wherein the coolant filter is replaceable, with the liquid-cooled heatsink coupled to the at least one electronic component to be cooled. 16.The cooled electronic module of claim 13, wherein the coolant-carryingcompartment comprises a converging inlet plenum converging towards theregion of reduced cross-sectional coolant flow area, and wherein thecoolant filter is disposed within the converging inlet plenum.
 17. Thecooled electronic module of claim 13, wherein the coolant filterencircles the region of reduced cross-sectional coolant flow area. 18.The cooled electronic module of claim 17, wherein the coolant traversesthrough at least a portion of the reduced cross-sectional coolant flowarea of the coolant-carrying compartment of the thermally conductivestructure and exhausts from the thermally conductive structure over theregion of reduced cross-sectional coolant flow area.
 19. The cooledelectronic module of claim 12, wherein the coolant filter is disposedwithin a coolant filter subassembly, the coolant filter subassemblycomprising a first end and a second end which couple in fluidcommunication with the coolant loop to facilitate flow of coolant withinthe coolant loop through the coolant filter, the first end and thesecond end comprising a first quick connect coupler and a second quickconnect coupler, respectively.
 20. A method comprising: providing aliquid-cooled heat sink configured to facilitate cooling at least oneelectronic component, the liquid-cooled heat sink comprising: athermally conductive structure with a coolant-carrying compartmentcomprising, at least in part, a region of reduced cross-sectionalcoolant flow area through which coolant flows; a coolant inlet and acoolant outlet associated with the thermally conductive structure and influid communication with the coolant-carrying compartment of thethermally conductive structure to facilitate coolant flow therethrough;wherein the region of reduced cross-sectional coolant flow area of thecoolant-carrying compartment provides an increased effective heattransfer coefficient between a main heat transfer surface of thethermally conductive structure and the coolant within thecoolant-carrying compartment; coupling a coolant loop to the coolantinlet and the coolant outlet of the liquid-cooled heat sink tofacilitate flow of coolant through the coolant-carrying compartmentthereof; and providing a coolant filter positioned to filtercontaminants from the coolant passing through the liquid-cooled heatsink, the coolant filter having a larger cross-sectional coolant flowarea than the region of reduced cross-sectional coolant flow area of thecoolant-carrying compartment within the thermally conductive structureof the liquid-cooled heat sink.